Thin skinned parabolic reflector with radial ribs



THIN SKINNED PAROBOLIC REFLECTOR WITH RADIAL RIBS Filed June 12. 1961 R. E. THOMAS Feb. 8, 1966 2 Sheets-Sheet l RICHARD E. THOMAS INVENTOR BY wmgfiiii R. E THOMAS Feb. 8, 1966 THIN SKINNED PAROBOLIG REFLECTOR WITH RADIAL RIBS Filed June 12, 1961 2 Sheets-Sheet 2 RICHARD E. moms INVENTOR United States Patent;

3,234,550 THIN SKINNED PARABOLIC REFLECTOR WITH RADIAL RIBS Richard E. Thomas, Baltimore, Md., assignor to Washington Aluminum Company, Inc., Baltimore, Md, a corporation of Maryland Filed June 12, 1961, Ser. No. 116,367 2 Claims. (Cl. 343-912) This invention relates generally to antenna structure, and more particularly it pertains to an improved reflector for electromagnetic radiation.

It is an object of this invention to provide a rigid light weight antenna reflector which is internally braced.

Another object of this invention is to provide an antenna disk having a continuous accurate reflecting surface suitable for frequencies high in the electromagnetic spectrum.

Yet another object of this invention is to provide an antenna reflector whose bracing structure is totally enclosed.

Still another objec-tof this invention is to provide a thin skinned reflector surface for an antenna dish which obtains its contour and strength from spaced radial arms, spacers, and clips.

These and other objects and attendant advantages of this invention will become more readily apparent and understood from the following detailed specification and accompanying drawings in which:

FIG. 1 is a plan view, partly broken away, of an antenna reflector incorporating features of this invention;

FIG. 2 is a side elevation of the antenna reflector taken along the line 2-2 of FIG. 1;

FIG. 3 is an enlarged view of a radial arm of the antenna reflector taken along line 33 of FIG. 1;

FIG. 4 is a cross section taken on the line 44 of FIG. 3;

FIG. 5 is a cross section taken on the line 55 of FIG. 3;

FIG. 6 is a cross section taken on the line 66 of FIG. 1; and

FIG. 7 is a perspective drawing of an intermediate spacer.

Referring now to the details of the drawings, and particularly FIGS. 1 and 2, the antenna reflector 10 of this invention includes a flanged cylindrical hub 12 from which a plurality of radially arranged arms 14 extend. Interme' diate their ends, the radial arms 14 are held in equal distribution about a full circle by means of spacers 16. The periphery of the reflector 10 is formed by spanning the ends of the radial arms 14 with closure sheets 18.

A metal parabolic central disk is secured over the aperture formed by the hub 12 and co-extensive with this disk 20, the effective reflecting area further includes a plurality of abutting metallic parabolic gores 22 and 24.

The under side of the antenna reflector 10 is covered with conical segmented sheets 26 and 28, thus forming a completely enclosed, smooth, weather proof structure. A flanged tubular pedestal 30 is secured to the bottom of the hub 12 for handling purposes.

As shown in FIG. 3, each radial arm 14 is made up of a tapered web plate 32 having one edge accurately cut to a section of a parabolic curve. Flanged lightening holes 33 are provided in the web plate 32 to reduce weight and increase the stiffness of the plate 32.

Upper and lower flange straps 34 and 36 are mounted on and conform to the edges of this plate 32 in the manner shown in detail in FIG. 4. For this purpose, spaced cleats 40, staggered on opposite sides, are secured to the web plate 32 by means of rivets 42.

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The flange straps 34 and 36 are fastened, in turn, to the cleats 40 by flush rivets 44. An inboard flange strap 38 is fastened in similar fashion to the inner edge of web plate 32. This flange strap 38 is used to mount each radial arm 14 to the hub 12 by means of rivets 48.

The ends of the radial arms 14 are each provided with outboard cleats 46 to which closure sheets 18 are secured by means of rivets 60.

The spacers 16 which distribute the radial arms 14 are pressed from a single piece of material so as to result in an arcuate wall 50 having opposing side flanges 52 and oppositely directed upperand lower flanges 54 and 56. It is to be noted the upper and lower flanges 54 and 56 are curved and dished to conform to the desired reflecting top area and bottom surface, respectively, of the com.- pleted assembly of the reflector 10.

The spacers 16 on opposite sides of the radial arms 14 are joined together with common rivets 58 which pass through the web plate 32. Thus, the assembled spacers 16 form a segmented ring situated on the median circumference of the antenna reflector 10.

Slanted U-shaped clips 62 are positioned intermediate the radial arms 14 as shown in FIG. 1 at the periphery of the antenna reflector 10. Clips 62 are secured, as illustrated in FIG. 6, to the outer parabolic gores 24 and outer conical segment sheets 28 to preserve the curvature of the closure sheets 18 and the desired dishing of the gores 24.

Each clip 62 is attached by its upper flange 66 to the respective gore 24 by means of flush rivets 72. The lower flange 68 and web 64 of the clip 62 are secured to the segment sheet 28 and to closure sheet 18 by rivets 74 and 70, respectively.

Flush skin rivets 76 are used to secure the gores 22 (and 24) to the straps 34 in the manner shown in detail in FIG. 5. Additionally, flush rivets 78 are used to secure the abutting curved edges of the gores 22 and 24 to the flange 54 of each spacer 16. Flush rivets 86 around the periphery of the central disk 20 attach the latter to overhanging inboard ends of straps 34.

It is to be noted that this construction and use of flush type rivets results in a smooth continuous reflecting area for the antenna reflector 10 devoid of any projections which might have deleterious electrical effect.

Ordinary rivets 8t) and 82 are suitable for use in securing the conical segment sheets 26 and 28 to the lower straps 36 and to the lower flanges 56 of the spacers 16, respectively.

Obviously many modifications and Variations of the present invention are possible in light of the above teachings. It is, therefore, to be understood that Within the scope of the appended claims the invention may be practiced otherwise than as specially described.

What is claimed is:

1. An antenna reflector having a continuous accurate reflecting surface, comprising, holding means including a centering element having an axially arranged aperture therethr ough, a plurality of radially arranged structural members extending outwardly from said centering element and each said structural member having its upper edge of parabolic shape, means radially spaced from said centering element for holding said radially arranged structural members in equal distribution about a full circle, means for spanning the peripheral ends of said radially arranged structure members, an electrically conductive parabolic central disk positioned over said aperture in said centering element, a plurality of electrically conductive abutting metallic parabolic gores arranged co extensively with said central disk and supported adjacent the upper parabolic edges of said radially arranged structural and said segmented sheets having each of their-edges cor respondingly secured to the upper and lower edges of said structural members, holding means; and spanning means, andpedestal means for mounting said centering element.

2. Th e antenna reflector as recitedin claim 1 where 10 said holding means consists of a Wall element positioned between each said structural members, with each said wall element having side flanges secured to their respective structural members and upper and lower flanges each conforming to the shape of said parabolic gores and said segmented sheets, respectively.

4 References Cited by the Examiner- UNITED STATES PATENTS 2,679,003 5/1954 Dyke et al 3439l2 2,985,881 5/1961 Holland et al 343-915 3,153,789 10/1964 Ashton 343912 FOREIGN PATENTS 1,013,721 8/1957 Germany.

OTHER REFERENCES Microwave Antennas Bulletin 428-A); published by Prodelin Inc. (Kearny, N1), 5 pages, one installation drawing (PID-2), June 6, 1958.

15 HERMAN KARL SAALBACH, Primary Examiner.

GEORGE N. WESTBY; Examiner. 

1. AN ANTENNA REFLECTOR HAVING A CONTINUOUS ACCURATE REFLECTING SURFACE, COMPRISING, HOLDING MEANS INCLUDING A CENTERING ELEMENT HAVING AN AXIALLY ARRANGED APERTURE THERETHROUGH, A PLURALITY OF RADIALLY ARRANGED STRUCTURAL MEMBERS EXTENDING OUTWARDLY FROM SAID CENTERING ELEMENT AND EACH SAID STRUCTURAL MEMBER HAVING ITS UPPER EDGE OF PARABOLIC SHAPE, MEANS RADIALLY SPACED FROM SAID CENTERING ELEMENT FOR HOLDING SAID RADIALLY ARRANGED STRUCTURAL MEMBERS IN EQUAL DISTRIBUTION ABOUT A FULL CIRCLE, MEANS FOR SPANNING THE PERIPHERAL ENDS OF SAID RADIALLY ARRANGED STRUCTURE MEMBERS, AN ELECTRICALLY CONDUCTIVE PARABOLIC CENTRAL DISK POSITIONED OVER SAID APERTURE IN SAID CENTERING ELEMENT, A PLURALITY OF ELECTRICALLY CONDUCTIVE ABUTTING METALLIC PARABOLIC GORES ARRANGED CO-EXTENSIVELY WITH SAID CENTRAL DISK AND SUPPORTED ADJACENT THE UPPER PARABOLIC EDGES OF SAID RADIALLY ARRANGED STRUCTURAL MEMBERS TO THE PERIPHERAL ENDS OF SAID RADIALLY ARRANGED STRUCTURAL MEMBERS FOR INCREASING THE EFFECTIVE REFLECTING AREA OF SAID REFLECTOR, SEGMENTED SHEETS COVERING THE UNDERSIDE OF SAID RADIALLY EXTENDING STRUCTURAL MEMBERS SO AS TO ENCLOSE SAID ANTENNA REFLECTOR; WITH SAID PARABOLIC GORES AND SAID SEGMENTED SHEETS HAVING EACH OF THEIR EDGES CORRESPONDINGLY SECURED TO THE UPPER AND LOWER EDGES OF SAID STRUCTURAL MEMBERS, HOLDING MEANS, AND SPANNING MEANS, AND PEDESTAL MEANS FOR MOUNTING SAID CENTERING ELEMENT. 